Where is my oversized sweater weather?

This last few days, scratch that, WEEKS have been hotter than any day I experienced this summer. They have been anywhere from 75 to 90 degrees. The real struggle though is not knowing how to dress for the day. This is basically what my daily routine has become:

7am: Cold enough to wear a t-shirt and jeans, maybe a sweatshirt.

7:45am: Walking to class, you start sweating, cause humidity decide to pick up in the last 45 minutes.

7:55am: You’re relieved cause the buildings are much cooler than outside.

8am: You start sweating again, because no part of these building are the same temperature.

9am: You get out of class and head outside to realize it is now 15 degrees hotter than when you first went to class.

PLEASE tell me anyone else has struggled with this. I literally have no idea how to dress for class in the morning so I end up going through like 3 different outfits. If any one has any tips let me know. I would greatly appreciate them, other wise share your stories if you can relate!